Preparation of sweetening medium from fruit



Patented June 3, i94

v Arvin Erickson, San Jose,

. Campbell, CaliL, assi Packing Company, rationof California gnors to Barron-Gray San Jose, C llie-,

No Drawing. Application September 11, ms, -SerlalNo.45'i,9'l5

' isciaims.

This invention relates to the preparation of sweetening media from sugar containing material. More particularly, it relates to an improved method for preparing sweetening media. fromfruit.

This application is a continuation-in-part of a copending application of the present inventors,

Serial No, 413,164, filed October 1, 1941.

It is an object of, the present invention to provide an improved method for preparing a sweetening medium from fruit.

- 1o, suflicient alkaline material is added as del Another object is :to provide an' improved method for preparing asweetening medium from fruit in which the difllcultly removable acidic impurities are eliminated and in which the treatment results in the formation of a granular and.

easily-filterable and washable, precipitate containing the undesired impurities together with added reagents.

Still another object is'to provide a method for eliminatlng impurities, addedreagents and insoluble solid portionsof the-fruitin a single separation step in which method the diflicultly removable acidic materials are eliminated with-' out at the same time givingto the liquid sugar containing portion .of the mixture a'colorwhich v is diflicult to remove thereafter.

Other objects will appear hereinafter.

It has now been found that the foregoing objects are accomplished by adding certain divalent alkaline materials to a mixture obtained by grinding fruit in any form until the pH of the liquid in the mixture is increased above pH 10.

to a pH where a precipitate separates out and which is at the same time sumciently high to result, upon subsequent treatment, as described hereinafter, in the formation of a granular, easily filterable and washable precipitate containing are obtainedincrystalline The present invention is applicable to the -.treatment of a-wide variety or diflerent'kinds and different kinds of sugars substantially all the acids and ash-forming 'materials in the mixture, including those added in the form of reagents. A

It has further been foundthat the increase of the pH of such a mixture to such a high point does not result in any permanent or difficultly removable color provided certain precautions are observed. These precautions are that the mixture be thereafter reduced to a pH below about 9.2 prior to filtration and that the mixture be kept at a temperature which is not substantially elevated, that is, preferably below about 54 degrees centigrade during the time when 'it has a pH in exces of about pH 9.2, that is, during at least the time when the latter part of the alkaline material is added and thereafter until the pH has been reduced with acid to below about 9.2. It is preferable to add acid-in sufll-- connection with the increase of the pH above termlned by laboratory test as herematter, the subsequent reduction of the DH with acid may be interrupted at a pH between about pH 9.2 and about pH '63, preferably below 8 and as near neutrality as possible, at which reduced pH a granular and easily filterable precipitate is obtained, particularly if the ature is increased 'tobetween about 54degrees centlgrade and the boiling point of. the mixture and that unsprecipitate will contain substan ash-forming materials tially 'all the acid and originally present in the fruit or added asheagents. Following the heating step the precipitate is then readily separated to leave a clear liquid by any desired filtering means. Ithas been found, however, that particularly good results are obtained if this separationis performed by an Oliver vacuum; filter, and preferably by a' filter of this typewhich is precoated with a filter aid. The resulting clear liquid is a sweetening. inedium containing a very high proportion 1 of the sugars originally present in the fruit.

It is substantially free of'acids andash-forming materials and has substantially the same sugar composition as that of the fruit'i'rom which it was, obtained. It deslreiiltmay beconeentrated and/or decolorized with an active form ofcarbon such asbone charor activated carbon to provide a water white syrup of any desired Brix concentration or, if desired, the concentra tion may continue to the'point where the sugars form.

of fruit materials containing different amounts and/or such as whole fruits or fruit wastes ormixtlu'cs of difl'erent kinds of fruits, for example, a mixture of fruits in the proportion in which they are packed in a single pack or during a whole operating season; By way of illustration, if, during the operating season, the total pack should be 70 per cent pears, 20 per cent peaches and '10 per cent gra s, the n0n-canning good portions of these fruits, which are normally wasted, could v be blended in this ratio before p to give theexact pH above cient, quantity to reduce the pH- below ,9.2

promptly after the reaction at the maximum pI-f Because the present invention is adapted to the treatment of a wide variety of fruits, the propertieSxOf which vary considerably, it is not possible 10 to which a particular ground fruit material is preferably raisedand it, is similarly impossible to give theexact pH between about pH 9.2 and about pH 6.3 at which such fruit material is preferably filtered following the addition of acid, This is true because the preferred treatment conditions for one batch ofv fruit may'be quite din'erent from those of'another due to variations in the characteristics of the two fruits or fruit wastes, but even between lots of the same variety of fruit. The preferred by adding the addition may be relatively rapid until a pH of batches. Such variations frequently occur not only between different kindsor mixtures of whole maximum pH and the preferred pH at which to carry out the filtration are, however, readily determined in any given case and in view of the possibility of variation even between different lots of fruit of the samevariety it is preferable to make a determination of the preferred maximum pH and preferred pH of filtration as described hereinafter on each batch of fruit treated.

The preferred pH finely ground fruit material is determined by taking a small batch of the'fruit material to be treated, grinding it to a fine pulp and then, while keeping the temperature below about 54 degrees centigrade increasing the pH of the fruit material divalent alkaline reagent. The

about is reached and it should then be continued slowly, preferably with constant agitation, until a pH is reached at which a definite break occurs. Usually the mass will turn to-a somewhat yellow color before this pH is reached. By a definite break is meant a break between solids and liquids resulting in the settling of the solid material to leave a portion ofclear liquid. As soon as this break occurs the addition of alkaline material is interrupted. Y when the break is reached a slight additional quantity of. the reagent is preferably added in order to be sure that the entire mixture is carried through the pH at which the break occurs. A sufilcient time (usually 10 to 20. minutes) is then allowed to permit the ceed to completion. Preferably during this period the mixture is agitated continuously or at least frequently. When sufficient time has been allowed to permit the mixture to reach equilibrium the pH is measured and recorded.

The acid reagent is then preferably added immediately with agitation to reduce the pH, the temperature still being kept below about 54 C.

' The additionof acid is preferably carried out different by very simple tests erably tested on the rate of filtration. Also the pH of the esulting filtrate is determined. This pH should be slightly lower than the pH to which the mixture was adjusted with acid prior to heating and if it is not, his an indication that the alkaline reagent was not given sufficient time to react at the maximumpH before adding the acid reagent.

Accordingly, where the pH of the filtrate is not lower than the pH prior to heating the test should be repeated as described above allowing to. which to increase the v resulting reaction to proslowly after the pH has been dropped below about 9.2. Below about pH 9.2 the pH is followed carefully as the acid is added and the pH beyond which further addition of acid down to pH 6.3 does not produce any further precipitate is noted. This is the optimum point at which to filter themass.

The addition of acid is preferably continued at least down to pH '1 in order to get the optimum point nearest neutrality.

Another batch of the fruit is then ground, the alkaline reagent is added as described above in sufiicient quantity to just carry the mixture through the pH at whichthe break occurs, the resulting mixture is agitated and allowed to reach equilibrium, then the acid reagent-is added to reduce the pH to the predetermined optimum nearest neutrality, the temperature as before being maintained below about 54 C. until the addition of the acid reagent is completed. Thereafter, the mass is heated until a granular precipitate is formed. This may occur depending upon the type of fruit anywhere from about 54 ('2. to the boiling point. As soon asa granular further heat until after filtration as further.

heating beyond the point where a granular precipitate is formed tends to cause a siiming.

Following the heating the mixture is then prefthe pH prior to increased time for the reaction at the maximum pH. If, on the other hand, the rate of filtration is too slow for practical production purposes, a

fresh sample of the fruit material is ground and suflicient 0f the alkaline reagent is added thereto to increase the pH to a pH higher than the previously determined maximum, for example,

to a pH about one-tenth of a pH unit higher than the previously determined maximum pH.

After agitating and allowing sufiicient time for the reaction at this higher pH to go to completion, the pH is measured and noted and the acid reagent is then added to this further test portion with agitation in the manner described above until the pH has been gradually reduced at least to approximately neutrality or down to pH 6.3, noting the pH nearest neutrality beyond which further additions of acid does not cause any further precipitation, both additions being carried I out below about 54 C. as described above.

Still another sample is then increased to the new maximum, brought to equilibrium and then reduced to the pH determined on. the preceding sample. This portion is maintained below about 54 C. until after the addition of the acid reagent and is then heated as described above-and tested on a Buchner'funnel and the pH of the filtrate is determined. If this pH is slightly lower than the pH prior to heating and if filtration now takes place at a satisfactory rate, the proper maximum pH and the proper pH to which to reduce the mixture following the increase to a maximum have now been determined for the whole batch of fruit. If filterability is still not satisfactory, or if the pH of'the filtrate is not slightly lower-than heating, the testing procedure is repeated, again increasing sample, and/or increasing the time allowed, for reaction at the maximum pH, determining the pH to which a sample'ralsed to the new maximum and/or actually brought to equilibrium at.the maximum pH should thereafter be reduced and again testing for filterability and pH of the filtrate, when employing these newly determined conditions. v

The above description of the test for determining the pH to which to increase the fruit material and the pH to which to subsequently reduce it prior to filtration is concerned particularly with the more general and preferred procedure in which the filtration takes place at a pH between about 9.2 and about 6.3. As pointed out hereinafter, however, it is occasionally necessary or desirable to filter at a pH even lower than 6.3, for example, as low as 5.3 or lower. One instance where such .lower pH may be desirable is in the treatment of certain tropical fruits in which sugars exist naturally at a relatively'low pH. It will be apparent to those skilled in the art, where satisfactory fiitrationis not obtained between 9.2 and pH-6.3, that the abovetest can be readily modified to determine the pH below 6.3 down to 5.3 or even lower at which satisfaca Buchner' funnel to determine the pH to a maxi--. mum slightly higher than that, of the preceding 3 T .dition of the reagents materialon a quantitybasis ratherthan on a basis. Addition of reagents on a quantity weight, 'basedon the weight sufficient to increase'the Thereafter, gallons of a heat and filter.

ed that such proper aj pH above 8 when the.

has been found that -cordance with the test tory filtration is obtained resulting in Separation of und'esiredimpurities.

It willbe appar nt that the would materials Employed in thejtest are preferably t at. preferably, but not necessarily, exactly the same reagents are employed; The use of exactly the same reagents is particularly desirable in commercial operation, since it facilitates the ad tothemainbatchoffmit P basis obviously'lends itself more readily to comthose to be usedin treating batch and sification mercialoperation' and has'been found to: give the I same results as addition on a pH basis when based on-a test. To this end in carrying out theabove described tests a measured sample of the, fruit material is employed in each'tost-and inj addi--" 'tion to noting the pH towhich the mixture should be increased with the alkaline reagent-and the pH to which it should be reduced with the acid reagent, the quantities of these two reagents which are required toieffect the pH adjustments the appropriate quantities ofreagents to produce the desired pH'conditicns therein can be readily calculated. De-' pendingupon the'nature of the particular batch of fruit material being treated, it has been found from about 1%, to about 4% of Ca (OHMfby of the pulp is usually pH to the proper point.

75%, by weight, aqueous solution .of H390: per ton of pulp is usually sufiicient toreduce the massto are also noted. Then the main batch of the fruit material is measured and from about 1% gallons to about 6 the proper pH at which to It isstated above that the proper pH at which to heat and filter is that nearest neutrality beyond which further additio of acid reagent do not give any further pH may be above pH 8. 5 It is generally desirable, however, to end up withv afiltrate having a the relatively few instances where the filtrate. has mixture is heated and filtered at the proper pH determined by; the test described above,

to. I acidity the filtrate itself to approximately neutrality and then filter again if. necessary. It addition of slightly more than the quantity of results and is definitely tering a second time if necessary. If the pH of the filtrate is below about 6.3, it is'preferable to add a small quantity of alkaline reagent to bring the pH up'to about pH. 7 and heat and filter,

again. Where theplii'of the filtratelies between precipitant and it is indicate.

7 (which is merely ait separates or brushes screen Among the vartested, the brush type. pulper .is preferred, since the skins, stems,.seeds,

cores, et cetera, from the pulpand gives afpurer initial pulp mass to treat, the skins, seeds, stems,

cores, et cetera,

being one of the principal sources of impurities.

The drying of certain fruits, such as prunes and raisins has a tendency, particularly when carried out over long periods with the aid of sun light, to form excessive quantities of dinicultly removable impurities. impurities to which reference to which the fruit material is, carried in accordance with the present invention, which color is difficult or impossible to eliminate. It has been found. however,

water prior to grinding them.

The wash water is preferably hot, although not ing the fruit is brought to a boil and be understood, tion of heat to pH below a. To thisend, in

it is preferable to heat and :fllter]- I at a pH sufliciently below that determined by I test to give a filtrate having a pH below 801- else does not include hot enough to scald the fruit. The, impurities in question are largely -on the surface of the fruit, and thus can'be washed off. After washput into water which has been of course, that the applicathis sterilizing water is discontinucd. at orbefore the in contact therewith.

general fruit material treated inaccordance with the present invention in its natural state sumcient water to insure the maximum extraction of the sweetening ingrediacld reagent required in ac- I data does not Meet the beneficial where it gives a filtrate havingapH nearer to'l. Also the filtrate is improved where its pH is above 8, if sufficient acidreagent is added to reduce it below 8 and, preferably to neutrality (pH 7) heating'and fil.--

- rated inthe Y more fully described.

. The water content of the treatment is preferably'adlusted to about the about 6.3 and 8, however, eventhough a pHnearer '7 is preferred, the filtrate is not ordinarily adjusted to a pH nearer neutrality, in this rangeis satisfactory for m st P poses.

In accordance with'the preferred procedure of:

since pH' the present invention, raw fruit'such as v pears, apples, grapes and the like, ordried fruit such as raisins and-prunes,- 'or the wastes from fruit packs suchas the wastes from peaches or the waste from'packing the fruit.. In general it fruit mat'erialof normalwater content the addients. In accordance with the preferredprocedure, therefore, water in some form is added to the'fruit material undergoing treatment at some point in the The process prior to the filtration step. water added may be'relatively pure water or water containing materials which are not undesirable, particularly water derived from other points in the system such as, for example, the

"sweet water from washing the precipitate sepafiltration step which is hereinafter mixture undergoing amount which will insure the complete-leaching out'of the sugars or sweetening ingredients in has been found that with tion'ofabout 10 percent of water by volume, based on the volume of flcient for this purpose. The amount. of water used even with fruit material of normal water content may, however, be varied considerably from 10 per cent within the, scope of the inven including an ordinary ham a fine screen) and a brush 4 the scream-the size and disintegration ofthe pulp is determined by the sizeoftheholesinthe ious types of grinding or disintegrating machines. .20

' The presence of the g is made frequently results in the formation of color at the high pH that these'impurities may bev l r ely eliminated by washing the dried fruits thoroughly in sterilized over night. It

time the fruit is brought the fruit material, is suf--v tion depending upon the material treated as well as upon other considerations and in the case of fruits of. abnormal water content, the amount preferably added varies widely. Thus, in the case of raisins, for example, the amount of water preferably added is of the order of 300 per cent, by weight, of the raisins, although both greater and lesser quantities may be used.

It will be apparent, of excessively large quantities of waterin any case increases the quantity of fruit material which must be handled and that on the other hand the presence of very small quantities of water may result in a pulp mixture which is too thick so that, for example, it does not heat readily, and in addition involves the danger that a substantial portion of the sugar will remain with the pulp and will not be extracted. Although however, that the presence water is generally added in accordance with the preferred procedure, its addition is not absolutely necessary. Furthermore, even in accordance with the preferred procedure the addition of water as such may be omitted in certain circumstances such as, for example, those where the fruit already contains large quantities of water and/or those where the alkaline reagent is'added to the pulp in very dilute form so that the water added with the alkaline material brings the water content of the mixture up to the minimum required for maximum extraction of the sweetening ingredients.

The addition of the water preferably takes place in connection with the grinding or disintegration of the fruit. that is, either just prior to, during or immediately after the grinding. The

advantage of adding the water prior to or during grinding is that it facilitates grinding and assists in avoiding air oxidation. As is well known, fruit exposed to air after the skin is broken rapidly oxidizes and turns brown, whereas if it is mixed with or covered with water this does not occur. There are, however, advantages connected with the addition of water even following the grinding which arise out of the increase in fluidity of the fruit material as a result of the-addition of water. This increased fluidity not only facilitates pumping of the pulped fruit to avessel in which it is to be treated for'elimination of impurities, but also aids in bringing about a better distribution of added reagents and in avoiding local high concentrations of added reagents and gives a longer time for leaching out of sugars.

Proceeding with the description of the preferred procedure, the ground or disintegrated fruit ma-,

terial preferably with its water content adjusted as described above, if necessary, is next treated with alkaline material. If a test has not already been made to determine the maximum pH to which to increase the fruit material with alkaline material, it' is made at this point, in the manner described in detail above, along with a determination of the pH to which the fruit material is thereafter reduced with an acid, preferabl notme also the quantities of the acid and alkaline reagents required to bring about the appropriate adjustments of pH.

A suitable alkaline reagent is added to the fruit material to raise the pH of the fruit material to approximately the maximum determined by test, as described, the'fruit material being maintained below about 54- degrees centigrade during this addition. As indicated above, although the addition of the proper quantity or the alkaline re agent may be determined by actually measuring the pH of the fruit material, it is preferable to measure the quantity of fruit material and simply add the quantity of reagent indicated by test'and calculation to give the proper maximum pH. Suitable alkaline materials with which to increase the pH are alkaline defecating agents. that is, alkaline materials, which are eliminated from the mixture at a later stage of the process and which are also capable of precipitating undesired impurities. Divalent alkaline materials, and particularly the alkaline earth metal oxides and hydroxides, such as the oxides and hydroxides of barium, calcium, strontium and magnesium have been found to possess the deslred'properties. The preferred divalent alkaline material is lime, particularly hydrated lime having a purity of 90% or high as 98% and which has a relatively low magnesium content (l /2% or less), but other'divalent alkaline materials both organic and inorganic may be used. Preferably also the divalent The alkaline reagent used is preferably a dilute aqueous solution or suspension of the alkaline material. The addition of the'alkaline material in the form of a dilute aqueous solution, particularly when accompanied by agitation of the mixture during and after the addition of the alkalinexeagent in accordance with the preferred procedure, aids in producing a homogeneous mixture and in avoiding local high concentrations of the alkaline material which are not desirable.

Following the addition of the alkaline reagent to the fruit material in sumcient quantity to increase the pHof the fruit material to the predetermined maximum, the agitation is preferably continued until the resulting reaction is completed. The time required for the completion of the reaction varies somewhat, as indicated above in describing the test, and it is preferable to allow from 10 to 20-minutes, or such other period as the test may indicate to be necessary for the reaction to take place, in order to be sure that it has proceeded to completion. After the agent, the fruit material, still maintained at a temperature below about 54 degrees centigrade is preferably acidified promptly with a suitable acid, as described above, in a quantity sufficient to reduce the pH to the pH, predetermined by test as described above, to be the pH beyond which fu'rthenadditions of acid do not produce any additional precipitate. In this case also the addition of the'proper quantity of acid reagent maybe determined by actually measuring the pH v of thefruit material, but it is preferable to measure the quantity of fruit material and simply add the quantity of reagent indicated by test and calculation to give the proper pH. The acid reagent used is preferably a dilute aqueous solution of the acid and it is also preferable to agiable to aid in producing a homogeneous mixture V and to aid in completing the reaction of the reagents.

The preferred acid with which to reduce the pH is phosphoric acid. While phosphoric acid is preferred because it gives consistentlygood 1esults in eliminating impurities, aids in eliminating color, and does not give undesirable properties to the syrups such as bad taste, other acids may be used for part or-all of the acidification but are not preferred because of their inferibetter and preferably a purity as ority in one respect or another to phosphoric acid. Suitable acidic materials to use are acid defecating agents, that is. any acid or combination of acids which when added in sufilcient quantity under the pH conditions specified will form insoluble compounds with the alkaline material used and will displace sugars from compoimds they form with said alkaline material without.

displacing undesired impurities from compounds they form with said alkaline material. Acids such as citric and sulfuric have been used where lime was the alkaline reagent, but neither of these gives as consistently good results as phosphoric acid.

Carbon dioxide or its corresponding acid, carbonic acid, is also capable of eliminating both the impurities and the alkaline material, but after the pH hasdecreased to 9.2 this acid dissolves lime to form bicarbonates. The bicarbonate may be eliminated, however, with'the aid of compounds .such as sodium carbonate or sodium aluminate, for example, by adding a small amount of such compound to the liquid filtrate and heating, preferably above 95 (2., prior to treatment with an active form of carbon.

It is stated above that both the alkaline and acid reagents are preferably dilute aqueous solutions or suspensions. the dilute solutions or suspensions of lime and phosphoric acid are preferably of the order of 10 to 20%, by weight. Lime or phosphoric acid solutions or suspensions having lower or somewhat higher concentrations may be used if desired. With solutions or suspensionsof higher concentrations,-it is preferable to exercise care during the addition to avoid local high concentrations of the reagent. The use of lower concentrations of the order of 6% *or considerably less, involves the handling of larger quantities of reagent, but it is advantageous in promoting better distribution of the reagent or where part of the water is to be supplied by the reagent solution.

Although the concentrations of the alkaline and acid reagents have been discussed together with particular reference to lime and phosphoric acid, it will be understood that in the treatment of any given batch of fruit material, it is byno means essential that the lime and phosphoric acids reagents be of the same or even approximately the same strength. Furthermore, the above discussion of concentration which particularly refers'to lime and phosphoric acid, is intended to be representative with respect to other alkaline and acidic materials. Appropriate concentrations of other alkaline and other acidic materials will be readily apparent to those skilled in the art or can be readily determined by a simple test. I

After the pH has been adjusted to the predetermined point by the addition of. the acid reagent, sufiicient time for reaction is preferably allowed and the mixture is then heated to a temperature between about 54 degrees eentigrade and the boiling point of the mixture to complete the reaction and bring about the precipitation of the maximum quantity of impurities in the form of a granular precipitate. As soon as this granular precipitateis formed it is preferable,

' to discontinue the heating immediately and amp ply no further heat until after filtration because further heating tends to cause a sliming which will interfere with filtration.

The mixture is now ready to be-filtered and The concentrations of solving any precipitated impurities.

ing mediums. The resulting filtrate is a sweetening medium in the form of a clear syrup and with or without further treatment described hereinafter, as preferred, is ready'for use. If desired a quantity of a filter aid maybe added to the treated mixture prior to filtration in order to improve its filtering character.

Suitable filter aids include calcium carbonate, diatomaceous earth and bagasselio. Due to the fact that the present proces yields a granular and easily filterable and washable precipitate, the addition of such filter aids is generally unnecessary and for some purposes, at least, is usually undesirable. Certain of the filter aids, for example, materially detract from the value of the separated solids when present therein.

The solid material separated by the above filtration is preferably washed to remove any small amount of sugar containing liquid or sweetening medium remaining therein. For this purpose ordinary water may be used or the pH of the water may be adjusted to approximately the pH of the filtrate, if desired, in orden to avoid redis- I'he washing is preferably continued until the precipitate contains less than about 1% sugars, by weight. The wash water is also preferably passed through the bag filter, if one is used, in order to wash out any of the filtrate which may remain in this filter. The wash water or sweet water fromsuitable for use to supply additional water to the original fruit material in order to provide sufiicient water to insure maximum extraction of the sweetening ingredients of the fruit. This sweet water may also be used instead of ordinary water as the diluent in making up the acid or alkaline reagent solutions or suspensions. It is generally preferable to return the sweet water into the system as a diluent, as described, since in this manner the sugar content thereof is not lost and at the same time the filtrate or sweetening medium is not diluted.

Where the filtration is conducted in accordance with the preferred procedure on an Oliver vacuum filter precoated with a filter aid, contrary to the above, it is preferable to include the wash water or sweet water in the filtrate. The

lowed to permit the completion of the filtration of the material which ispicked up on the surface of the filter aid, and also to permit washing of thisfiltered material before the scraper knife is reached. Sprays of wash water are positioned to spray wash water onto the solids after their filtration is substantially complete, this wash water then passing into the interior of the drum along with thefiltrate.

In accordance with the preferred procedure as described above, this filtration may be accomq K the wash water is supplied at an elevated tom- Preferably, where the precoat perature between about 54 C., and the boiling point. Preferably ithis wash water will have substantially the same temperature when it strikes the solids on the surface of the drum, as the mixture undergoing filtration has. It has been found,-in general, that about by volume of wash water based on the volume of fil ing medium is to be used in fruit of the same type from which it is derived. The removal of these materials is not essential, therefore, although it is preferred.

Some materials of this type, particularly those.

imparting color, are usually present in the clear filtrate from the filtration step described above. Preferably, thereiore, this clear filtrate is treated with an active form of carbon such as animal bone char or activated carbon whereby any coloring material. and any materials imparting odorand flavor which may still be present are removed. The clear filtrate i ordinarily substantially neutral since the pH at which filtration takes place is preferably as near neutrality as possible, although r with ionexchange bodies.

the pH of the clear filtrate may not be exactly 7.

The Oliver vacuum filter may also be used very conveniently in the decolorizing of the filtrate with an active form of carbon. For this purpose only a very thin layer of precoat material or filter aid is applied and then, in the same manner'that the precoat material is applied, a layer of finely divided active, carbon, such as a layer of bone char or activated carbon is built up on the filter drum ontop of the thin layer of precoat material. This layer of active carbon is generally from to 1 inch in thickness, depending on the precoat material, and may be as thick as 2 inches or more. It is preferably built up to as thick a layer as possible which will not break off in operation of the filter. Active carbon is also added to the filtrate to be decolorized to crystallize out any sugars, since the syrup form.

of the sweetening medium is entirely satisfactory for most purposes and in fact is preferable. If a slightly caramelized color appears after concentration, the medium can be again decolorized over the bone char or activated carbon. Concentration is carried out in a conventional manner by evaporation accelerated by the use of heat. If

.desired, it may be continued to the point where the sugars are deposited out of the solution in crystalline form, although this is not usually done as indicated above. For example, in making a sweetening medium for a fruit pack, concentration may be omitted entireiyor may be stopped after it has, progressed to the point where a moderately thick syrup has been formed which is suitable for the packing of fruit.

Although it is generally unnecessary, the purity of the sweetening media may be further 111-" creased in some cases, if desired, by treatment As examples of such materials mention is made of base exchange bodies, such as zeolites, permutit and amines.

The pulp and the material precipitated during treatment which are left behind when' the sweetening medium is separated as, for example, by filtration, are valuable and can be dried andused for various purposes, preferably after washing as described above. For example, this material is suitable for use as a fertilizer.

It is, of course, preferable to add to any batch of fruit just the quantities of reagents required to give'the optimum pHs, predetermined by test as described above. The invention is not, however, intended to be limited strictly to the use of the optimum conditions. Moderate variations from the optimum points do not greatly affect I the results and such moderate variations are, therefore, within the scope of the invention.

Furthermore, the present invention includes within its broadest scope the treatment of either the mixture obtained by grinding fruit, which includes both pulp and juices, or the treatment of a juice separated from such a mixture by a process involving the-following steps:

(a) A divalent alkaline material such as lime, preferably in the form of a dilute aqueous solution or suspension is added to either the foregoing pulp-'juice mixture or to a juice separated therefrom in an amount suflicient to increase the pH of the mixture or juice to a pH above 10, at

- which diflicultly removable organic acids are on the filter drum substantially uniformly at its initial thickness. As described above wash water is sprayed onto the surfacesof the drum to sweeten off or wash out the sugars in the layer .of-active carbon. The foregoing provides a ve y convenient and efl'icient methodfor removingthe cracked or react with the-added reagent, the temperature of the mixture or juice being maintained below about 54 degrees centigrade during at least the latter part of the treatment, that is, during at least the time when the pH is 'above about pH 9.2. v

(b) The pH is reduced preferably immediately after the addition, thorough distribution and re.- action of the alkaline reagents in step (a) is completed by adding an acid reagent, preferably in the form of an aqueous solutioncomprising -a suitable acid, as described above in an amount treating carbon and is particularly advantageous from the standpoint of washing or sweetening ofl the carbon.

The clear filtrate or sweetening medium may be concentrated to any desired extent, but concentration preferably, but not necessarily, follows the treatment with bone char or carbon. Usually concentration is not carried far enough sumcient' to give the composition a pH below about pH 9.2, and at which a substantial quantity" of impurities are precipitated out, the temperature still being maintained below'about' 54 degrees centigrade during at least the initial stages of the acid reagent addition, that is, until the pH has been reduced below about pH 9.2. The temperature is preferably maintained below about 54 degrees centigrade from the first addition of the alkaline reagent until the, addition of the acid reagent is completed. Permitting the temperature anaeroto riseabove 54 degrees centigrade while thepH .is as high as 9.2 or higher, may result in giving the composition a' color which is diflicult or impossible to eliminate thereafter, and it is because some tendency in this direction is'noted; even after the-pH has been reduced to a pH as low as 7.6 to 8, that maintenance of the temperature below about 54 degrees centi'grade is'preferable during the entire treatment describedin steps (a) and .(b). Whereas the temperature is preferably kept low as described above during the addition of the acidand alkaline-reagents, it is preferable to increase the temperature after the addition of these reagents i completed in order to insure completion'of the reaction or reactions washed with water until the solids contained less taking place, which result in the precipitation of 1 the impurities. By way of illustratiom the pH to which the juice or mixtureis reduced by the addition of acid in step (b) may be between about pHiLZ and about 6.3, as disclosed above, or may than;1 Mars and these washings were added to the clear filtrate. The'washed solids were removed and dried for disposition as fertilizer or for other purposes. The clear filtrate, together with the washings, was decolorized over bone char in the conventional manner to providea sweetening 'medlmn in. the form of a clear, substantially .water white syrup. which could be further concentrated or used as such.

be in the definitely acid pH' range, for example, 1

between about pH 4 and about p116; as disclosed in the above-mentioned copendingapplication oi which this application is a continuation-in-part. or may be between these two ranges, and following the heating to complete the reactions the Juice, or mixture may be given any desired -addi-' tional treatment in order to produce a; sweetening medium therefrom, or improve the characteristics of theresultlng sweetening medium. For ex- .two thousand pounds of pears, peaches and grapes originally contained three hundred' and twenty-six pounds of total sugars. Analysis of, a sample of the original juice showed a sugars purity of 56%. The final syrup product was found on-analysis to contain two hundred and eninety-three pounds of sugars or in other words, of the, three hundred and twenty-six pounds of sugar in the original fruit material two hundred and ninety-three-pounds were recovered in the ample, where the pH of the filtrate is above about 8 or below about 6.3, it is preferablev .to adjust 7 the pH of the filtrate to about 7 with the acid or alkaline reagent, as the case may be, and then.

heat and filter again. Similarly the mixture or juice may be given any desired treatment prior to the addition of the alkaline material.

To further facilitate understanding of the improved method of preparing sweetening media from fruit which is disclosed herein, the followfinal syrup product. represents a yield of and indicates that the efllciency of the extraction is excellent. In addition 'the sugars purity of the final product is also greatly im-.

proved, being 78%.

The process described and illustrated above eliminates mm the mat those materials originallypresent'or added as reagents which when present'detractfrom the sweete ing pqwer oi ing detailedexample is given. 'Ihisexampleis merely illustrative and is not intended to be construed as limiting the scope of the invention.

I Example I Two thousand pounds of amixture of pears, 20% peaches and 10% grapesi er verized through a brush separator. Ten percent by volume of water was then added to the pulverized fruitini order to provide sumcient water to insure maximum extraction. of the sweetening ingredients. Lime in the form of 10 Brix aqueous solution was then added to the diluted pulpjuice mixture in a tan]; provided with an agitator and with meansffor heating the tank; The addition of the lime reagent with simultaneous agitation was continued until the pH of the mixture" was increased to pH'1;l.-i, indicated by'previous 10 to which to increase the pH of the "mixture with lime, and agitation was continued thereafter until the lime was thoroughly distributed and the resultingreaction complete. About 15 minutes was allowedfjor this purpose after the lime had all been added.

When the reaction resulting upon the addition and thorough distribution of thelime was complete, the pH. of the; mixture was then reduced" topH 7-.6 by-addingphosphoric acidiri the-form of a 10 Brix aqueous solution, the mixture being v final product is thus a sweetening medium. Theprincipal materials-which detract from thesweetening power of the sugars in fruit compositions arethe acids'and bitter salts,

. particularly the organic acids. and these are substantially eliminated by the; process described.-

are, of course, .other-wat'er-soluble nonsugars present in the original fruit material and I a substantialportion of these is carried over into the final sweetening medium product, as evidenced by the ifact that the sugars'purity of the -products isnot usuallycne hundred percent when the mediumds finished oil. in' syrup form.

These non-sugars which remain cannot really be regarded as impurities because they are inert and "do not have'any adverse effect on th sweetening 1 power of the sugars present. Furthermore, they are constituents of the fruit from which the sweetening rnedium is derived, and where the, latter is to bje added to fruit these non-sugars are I V the; same. as materials already present in the test as described above to be the proper pH above 111mb nm'sugars may be eliminated edlyherein, and in the light of the foregoing agitated during the addition of'the acidltoinsurel',

its thorough distribution. Following the grinding' and addition of water, as described above; care was taken to seethat. the temperature ofthe mixture-was at all times maintained below sugarsin acommon solvent. L'I'he advantages-prime present explanation'it will-be understood that it means just whatthename signifies, i. e.,- a sugar con.-

taining medium which'is substantially free of materials which detract from the sweetening 'power of the sugars present,- such as acids and ash- -forming materials, although it may contain substantial quantities of inert diluents;

Sugars purlty,- as used herein, is expressed in, terms '01 the-quantity of sugars as related to the, Mal-"solid materials 'in'solution with the invention J be apparent from the foregoing description in large part. One of the chief merits of the process is that it is simple and inexpensive to carry complished, moreover, without. any substantial decrease in the purity of the final product or materialdecrease in yield usually with an improvement in the color of the filtrate.

. The percentage of sugar recovered from the fruit material in a useful form is exceedingly high, very little sugar being left behind in theiilter cake or destroyed in the purification operations.

It'is apparent that many widely diiierent embodiments of this invention may be made with- 1 out departing from the spirit and scope thereof,

and, therefore, it is not intended to be limited except as indicated in the appended claims.

We claim:

1. In thed rocess of preparing a sweetening medium from fruit, the steps which comprise adding an alkaline defecating agent to a composition obtained by grinding fruit material and comprising the sweetening ingredients of the fruit in an amount sufllcient to increase the DH .of the fruit composition to substantially the pH above 10 at which abreak occurs and which resuits in the formation subsequently of a granular, readilyfilterable and washable precipitate, then when the reaction at this pH is complete, adding an .acid defecating agent in an amount suflicient to reduce the pH of the composition to a pH between about pH 9.2 and about pH 6.3, at which said granular, readily fllterable and washable precipitate is formed, and thereafter separatingthe precipitate so formed to leave a clear liquid, said composition being maintained at a temperature below about 54 C. at least during the time when'it has a pH above about 9.2

2. In the process of preparing a sweetening medium from fruit, the steps which comprise adding an alkaline defecating agent .to a compo- "sition obtained by grinding fruit material and comprising the sweetening ingredients of the fruit in an amount suflicient to increase the pH of the fruit composition to substantially the pH rial being added in an amount sufficient to increase the pH of the fruit composition to substantially the pH above 10 at which a break occurs and which results in the formation subseresulting saving in time and equipment is acquently of a granular, readily filterable and washable precipitate, then when the reaction at this'pH is complete adding an acid defecating agent in an amount suiiicient to, reduce the pH of the composition to a' pH between about pH 9.2 and about pH 6.3 at which said granular, readily fllterable and washable precipitate is formed, "and thereafter separating the precipitate soformedto leave a clear liquid, said composition being maintained at a temperature below about 54 C. at least during the time when it has a pH above about.9.2.

4. In the process of preparing a sweetening medium from fruit, the steps which comprise adding a-divalent alkaline defecating agent to a composition obtained by grinding fruit material and comprising the sweetening ingredients of the fruit together with acids and ash-forming materials of the fruit, said divalent alkaline material being added in an amount sufllcient to increase the pH of the fruit composition to substantially the pH above 10 at which a break oc- 7 curs and which results in the formation subsequently of a granular, readily 'fllterable and washable precipitate, then when the reaction at this pH. is complete adding an acid defecating agent in max mum: sufllclent to reduce the pH of the composition to a pH between about pH 9.2 and about pH 6.3 at which said granular, readily fllterable and washable precipitate is formed, heating the composition to a temperature between about 54' C. and the-boiling point of the mixture to complete the formation of the precipitate, and thereafter separating the precipitateso formed to leave a clear liquid, said composition ,being maintained at a temperature below about 54 C. until the addition of said alkaline material and said acidic material is complete.

5. In the process of preparing a sweetening medium from fruit, the steps which comprise adding lime to a composition obtained by grinding fmitmaterial and comprising the sweetening ingredients of the fruit together with acids and ash-forming materials of the fruit, said lime being added in an amountsuflicient'to increase the pH of the fruit composition to substantiallythe pH above 10 at which a break occurs and which results in the formation subsequently of a granular,'readily"fl1terable and washable precipitate,

above 10 at which a break occurs and which resuits in the formation subsequently of a' granular, readily filterable and washable precipitate, then when the reaction at this pH is complete adding an acid defecating agent in an amount, suflicient to reduce the pH of the composition to medium fromfruit, the steps which comprise then, when the reaction at this pH is complete,

adding phosphoric acid in an amount sufficient to reduce the pH of the composition to a pH between about pH 9,2 and about pH 6.3 at which said granular, readily iilterable and washable precipitate is formed, and thereafter separating the precipitate so formed to'leave a clear liquid, said composition being maintained at a temperature below about 54 C. at least during the time when it has a pH above'about 9.2.

6. In the process of preparing a sweetening medium from fruit, the steps which comprise adding lime to a composition obtained by grinding fruit material and comprising the sweetening ingredients of the fruit together with acids and ash-f0rmin8 materials of the fruit, said lime beadding adivalent alkaline defecating agent to a composition obtained by Grinding fruit material and comprising the sweetening ingredients of the fruit together with acids and ash-forming materials of the fruit, said divalent alkaline matein: added in an amount suiiicient to increase the pH of the fruit composition to substantially the pH above 10 at which a break occurs andwhich results in the formation subsequently of a gram ular, readily filter-able and washable precipitate, then, when the reaction 'at this pH is complete,

17 adding phosphoric acid in an amount suflicient to reduce the pH of the composition to a pH between about pH 9.2 and about pH 6.3 at which said granular, readily filterable and washable precipitate is formed, then heating the composition to a temperature between about 54 C. and the boiling point of the mixture to complete the formation of the precipitate, and thereafter separating the precipitate so formed to leave a clear liquid, said composition being maintained at a temperature below about 54 C. at least during the time when it has a pH above about 9.2.

'7. In the process of preparing a sweetening medium from fruit, the steps which comprise adding lime to a composition obtained by grinding fruit material and comprising the sweetening ingredients of the fruit together with acids and ash-forming materials of the fruit, said lime being added in an amount sumcient to increase the pH of the fruit composition to substantially the pH above at which a break occurs and which results in the formation subsequently of a plete, adding phosphoric-acid in an amount sufficient to reduce the pH of the composition substantially to a pH between about pH 9.2 and about pH 6.3 at which said granular, readily filbeing maintained at a temperature below about granular, readily fllterable and washable precipi-r tate, then when the reaction at this pH is comterable and washable precipitate is formed and below which further additions of phosphoric acid do not produce any additional precipitate, then heating the composition to a temperature between about 54 C. and the boiling point of the mixture to complete the formation of the precipitate, and thereafter separating the precipitate so formed to leave a clear liquid, said composition being maintained at a temperature below about 54 C. at least during the time when it has a pH above about 9.2.

8. The process of preparing a sweetening medium from fruit which comprises adding dilute aqueous lime to fruit in the form of a finely ground pulp from which at least the skins, seeds, stems and cores have been separated and which contains suflicient water to insure maximum extraction of the sweetening ingredients, said lime being added in an amount sufiicient to increase the pH of the fruit composition to substantially the pH above 10 at which a break occurs and which results in the formation subsequently'of a 54 C. at least during the time wh'enit has a pH above about 9.2.

10. In the process of preparing a sweetening medium from'fruit, the steps which comprise adding an alkaline defecating agent to a composition obtained by grinding fruit material and comprising the sweetening ingredients of the fruit together with acids and ash-forming materials of the fruit, said alkaline material being added in an amount suflicient to increase the pH of the composition above pH 10 to a pH at which a precipitate separates out and which results in the formation subsequently of a granular, readily filterable and washable precipitate, thereafter adding an acid defecating agent in an amount sufficient to reduce the pH of the composition to a pH below about pH 9.2 at which said granular, readily filterable and washable precipitate is formed and thereafter separating the precipitate so formed to leave a clear liquid.

11. In the process of preparing a sweetening medium from fruit the steps which comprise adding an alkaline defecating agent to a composition obtained by grinding fruit materialand v comprising the sweetening ingredients of the fruit together with acids and ash-forming materials of the fruit, said alkaline material being added in an amount sufiicient to increase the pH of the composition above pH 10 to a pH at which a precipitate separates out and which results in the formation subsequently of a granular, readily filterable and washable precipitate, thereafter adding an acid defecating agent in an amount sufiicient to reduce the pH of the composition to a pH below about pH 9.2 atwhich said granular, readily filterable and washable precipitate granular, readily filterable and washable precipitate, then when the reaction at this pH is complete adding dilute aqueous phosphoric acid in 1 an amount predetermined by test to be suflicient to reduce the pH of the composition to a pH between about pH 9.2 and about pH 6.3' at. which any additional precipitate, then heating the com'-.

position to a temperaturebetw'eerr about 54 C. vand the boiling point of the mixture-to complete is formed, and thereafter separating the precipitate so formed to leave a clear liquid, said composition being maintained at the pH above 10 until the resulting reactionis completed and then promptly reduced below about pH 9.2 by adding said acidic material -and said composition being maintained at a temperature below-about i 12.- In the process of prepaiving -a sweetening medium from fruit; the ste'ps which comprise 'addillg an alkaline 1 defecatingiagent V to; a composition-obtained by grinding. ruit' material and the formation of the precipitate, and thereafter separating the precipitate so formedto leave a clear liquid, said composition being maintained at a temperature below about 54 C.- until the addition of said lime and phosphoric acid is completed. .2

9. In the process of preparing a'sweetening medium from fruit, the steps which comprise adding an alkaline defecating agent to a composition obtained by grinding fruit material and comprising the sweetening ingredients of the fruit to ether with acids and ash-forming materials of the fruit, said alkaline material being 75 comprising the sweetening; ingrdiehtsmf the fruit together with :acids' aridiash rforniing ma- "terials' of the fruit,*saidihlkalineamaterialbeing added in an -amount-rsuifficientl'tosincrease the pHofthe composition abdye.=fipE ll) to a'pH at which a precipitate separatesidut and which results in the formationasubsequently of agranu- 'lar, readily -filterable and ffwashable precipitate.

thereafter addinganaciddefecating agent in an amount sufiicient to reduce'the'pH'of the composition to a pH'below about/pH 9.2 and bring the composition ultimately to a pH where said granular, readily filterable and washable precipitate is formed and where, upon filtration, a ill- 54 0. at leastduring the: time when-ithas a pH o abbutaa 1 1 formed to leave a clear liquid, said composition being maintained at a temperature below about 54 C. at least during the time when it has a pH above about 9.2.

13. In the process of preparing a sweetening medium from fruit, the steps which comprise adding an alkaline defecating agent to a composition obtained bygrinding fruit material and comprising the sweetening ingredients of the fruit together with acids and ash forming materials'of the fruit, said alkaline material being addedin an amount sufficient to increase the pH of the composition above pH to a pH at which a precipitate separates out and which results in the formation subsequently of a granular, readily filterable and washable precipitate, thereafter adding anacid defecating agent inan amount suflicient to reduce the pH of the composition to a pH below about pH 9.2 at which said granular, readily filterable and washable precipitate is formed, and thereafter separating the precipitate so formed to leave a clear liquid, said'composition being maintained at a temperature below about 54 C. until the addition of said alkaline material and said acidic material in sufilcient quantities to form a precipitate as described above is completed.

14. In the process of preparing a sweetening medium from fruit, the steps which comprise adding an alkaline defecating agent to a composition obtained by grinding fruit material. and comprising the sweetening ingredients of the fruit together with acids and ash forming materials of the fruit, said alkaline material being addeddn an amount sufficient to increase the pH of the composition above pH 10 to a pH at which a precipitate separates out and which results in the;

formation subsequently of a granular, readily fiiterable and washable precipitate, thereafter adding an acid defecating'agent in'an amount sufficient to reduce the pH of the composition 'to a pH below about pH 9.2 at which said granular,

. readily fiiterable and washable precipitate is formed, and thereafter separating the precipitate so formed to leave a clear liquid, said composition being maintained at a temperature below about 54 C. until the addition of said alkaline material and said acidic material in sufllcient quantities to form a precipitate as described above is completed, and being then heated to a temperature between about 54 C. and the boiling point of the mixture to complete the formation of the precipitate. 4

15. In the process of preparing a sweetening medium from fruit, the steps which comprise adding a divalent alkaline defecating agent. to

20 v precipitate so formed to leave a clear liquid. said composition being maintained at a temperature below about 54 C. at least during the time when it has a pH above about 9.2.

16.--In the process of preparing 'a sweetenin medium from fruit, the steps which comprise adding a divalent alkaline defecating agent to a composition obtained by grinding fruit material and comprising the sweetening ingredients of the fruit together with acids and ash-forming materials'of the fruit, said divalent alkaline material being added in an amount sufficient to'increase the .pH of the composition above pH 10 to a pH at which a precipitate separates out and which results in the formation subsequently of a granu lar, readily fllterable and washable precipitate, thereafter adding phosphoric acid in an amount suflicient to reduce the pH of the composition to a pH below about pH 9.2 at which said granular, readily fiiterable and washable precipitate is formed, and thereafter separating the precipitate so formed to leave a clear liquid, said composition being maintained at a temperature below about 54 C. at least during the time when it has a pH above about pH 9.2.

17. In the process of preparing a sweetening medium from fruit, the steps which comprise adding lime to a composition obtained by grinding fruit material and comprising the sweetening ingredients of the fruit together with acids and ash-forming materials of the fruit, said lime being added in an amount sufficient to increase the pH of the composition above pH 10 to a pH at which a precipitate separates out and which results in the formation subsequently of a granular, readily fiiterable and washable precipitate, thereafter adding phosphoric acid in an amount sufficient to reduce the pH of the composition to a pH below about pH 9.2 at which said granular, readily fllterable and washable precipitate is formed, and thereafter separating the precipitate so formed, to leave a clear liquid, said composition being maintained at a temperature below about 54 C. at least during the time when it gredients of the fruit together with acids and ash-forming materials of the fruit, said lime being added in; an amount suflicient to increase the pH of the composition above pH 10 to a PH a composition obtained by grinding fruit material and comprising the sweetening ingredients of the fruit together with acids and ash-forming materials of the fruit, said divalent alkaline maat which a precipitate separates out and which results in the formation subsequently of a granular, readily fiiterable and washable precipitate,-

thereafter adding phosphoric acid in an amount sumcientto reduce the pH of the composition to a pH below about: pH 9.2 at which said granular, readily fiiterable and washable precipitate is formed, and thereafter separating the precipitate so formed to leave a clear liquid, said composition terial being added in an amount sufllcient to i increase .the pH of the composition above pH 10 to a pH at which a precipitate separates out and which results in the formation subsequently of a tate, thereafter adding an acid defecating agent in an amount sufficient to reduce the PH of the composition to a pH below about pH 9.2 at which said granular, readily fllterable and washable precipitate is formed, and thereafter separating the granular, readily filterable and washable precipibeing maintained at a temperature below about 54" 0. until the addition of said phosphoric acid and said lime in suillcient quantity to form a precipitate as described above is completed; and being then heated to atemperature between about 54 C. and the boiling point of the mixture to complete the formation of the precipitate.

ARVID'M. nmcxsou. JOHN 1). RYAN.

Certificate of Correction Patent No. 2,421,376. June 3, 1947.

' ARVID M. ERIOKSON'ET AL.

' It is hereby certified that errors appear in the printed Specification of the above numbered patent requiring correction as follows. Column 5, line 41, for precipitant read precipitate; column 15, line 32, claim 1 and line 52, claim 2 after the word fruit LESLIE FRAZER,

First Assistant Oommissioner of Patents. 

